The invention relates to an adjustable head-up display (HUD) arrangement for a vehicle, for example suitable for tuning a perceived distance to projected information based on a current speed and application type of the vehicle. The invention also relates to a corresponding method for operating the HUD and to a thereto related computer program product.
In a modern ground vehicle there is a multitude of in that may be provided to a driver. Such information may for example include the current vehicle speed, the engine rotational speed, fuel level or the oil temperature, as well as traffic and navigation data or even display from different smartphone app information. The information is usually displayed on an instrument panel. When reading the displayed information from the instrument panel the driver is distracted at least for a short time from the traffic situation. Head-up displays (HUDs) make it possible to display graphical information, such as by means of a virtual image, directly in the field of view of the driver on the windshield of the vehicle or using a transparent media placed in front of it. In this way, information content provided with the virtual image can be comprehended while the road conditions remain in the driver's field of view.
For achieving a desirable driver ease in viewing the viewing image, it is generally a necessity to be able to adjust the position of the virtual image about its nominal position the better to adapt it to the height of the driver's seat, to his height and to the geometry of the vehicle. As exemplified in U.S. Pat. No. 5,034,732, also a vehicle context will have impact on how the virtual image is to be displayed to the driver. For example, the driver's eye direction is different between when the vehicle is running, in a city at low speed and when running on a speedway at high speed. In U.S. Pat. No. 5,504,732, this is handled using a half mirror reflecting means that is controlled as to its height and angular positions. The control is performed automatically based on a sensor detecting the speed of the vehicle.
Even though U.S. Pat. No. 5,034,732 discloses an interesting technical implementation for dynamically taking into account also contextual aspects in operating a vehicle, the suggested implementation will be somewhat bulky and not suitable for a modern type vehicle compartment having high constrains on available space. In addition, there would be desirable to allow for further flexibility in displaying a virtual image to a driver of a vehicle, specifically for commercial vehicles such as trucks and buses.
According to an aspect of the invention, the above is at least partly alleviated by a head up (HUD) display arrangement for a vehicle having a windshield, comprising a combiner, the combiner embedded on or arranged in a vicinity of the windshield, and a projector optically connected to said combiner, said projector projecting graphical information on said combiner, the graphical information perceived at a graphical information distance in front of the combiner, wherein the head-up display arrangement further comprises a lens arrangement arranged in an, optical path between the projector and the combiner, the lens arrangement comprising a plurality of axially aligned lenses, wherein at least one of the plurality of lenses is axially movable along the optical path for automatically adjusting said graphical information distance.
The present inventors have identified that it is desirable to be able to adjust not only the horizontal and vertical sight angles as has been proposed by means of previously known HUDs, but also allow for an adjustability of a perceived distance to the graphical information provided at the windshield. This is specifically apparent in a commercial vehicle, such as a tack or a bus, where the driver is arranged in an elevated position as compared to a passenger car. Mat is, the driver will greatly change his line of sight depending on the speed and the context of operating the vehicle. Thus, there will be a relatively large difference in focal) distance to the projected graphical information.
In accordance to the invention, the adjustability of the perceived distance, denoted as graphical information distance, is achieved using a flexible lens arrangement comprising a plurality of axially aligned lenses that may be repositioned along an optical path. The proposed lens arrangement may be implemented in a compact manner, thus making it advantageous for use in relation to a modern vehicle compartment. The repositioning may be performed dynamically and fast, thus allowing for an improved flexibility to handle quick changes in e.g. speed and context. Furthermore, the introduced flexibility makes it possible to swiftly position the graphical information at an angle that is slightly lower or higher than an “object of interest” visible through the windshield, as not to hide the object and its immediate surroundings. In an embodiment the context for the driver is dependent on a driver state monitoring (DSM) system arranged to monitor the behavior of the driver. The output from the DSM system may then be used as an input for controlling the graphical information distance.
The combiner may, as indicated above, be provided as an integral part of the windshield (possibly being a front, side or back window, typically being a front window) or as a separate part arranged close to the windshield. The combiner can be formed as a semi-reflective mirror (flat or curved) or diffractive combiner (i.e. a combiner that deviate the light towards the user by means of an optical diffraction grating). The combiner may for example be made from a glass or a plastics material.
In an embodiment of the invention, the lens arrangement comprises at least three lenses, including a fixed lens and at least a first and a second axially movable lens. The first and a second axially movable lens may typically be positioned to control a focal distance of the graphical information projected onto the combiner. An electronically controlled actuator, such as a motor, may be provided with each of the first and a second axially movable lens, allowing for axial reposition of the respective lenses.
In a preferred embodiment, at least seven lenses are provided with the lens arrangement, including three fixed lenses and four axially movable lenses. The further lenses (i.e. as compared to the previously mentioned three lenses) allows for an even further tuning of the focal distance, at the same time making easier to apply to the physical size constrains as mentioned above. That is, using an increased plurality of lenses allows for only small movements to be needed for achieving the desired adjustment of the focal distance and thus the resulting graphical information distance.
Preferably, the lens arrangement is configured such that it is possible to allow the graphical information distance to be adjusted at least between 2 and 8 meters. The exemplified distance range is of course dependent on the specific implementation, type of vehicle, etc. and may hence result in a wider or narrower distance range. However, in case of allowing the graphical information distance to be adjusted to between 2 and 8 meters it is typically possible to handle typical speed and contextual scenarios for the vehicle. It should be understood that the graphical information distance also may, as indicated above, be adjusted based on an elevated height of a driver compartment of the vehicle in relation to a ground level.
In a possible embodiment of the invention the lens arrangement is configured to be constantly adjusted by axially moving the at least one lens along the optical path, typically with a frequency at or above 30 Hz. By means of allowing such control the graphical information distance may be set dynamically, typically suitable for an augmented reality application where the provided graphical information is matching the location of real-world information actually viewed by the driver, for example in various driving environments.
The projector preferably comprises at least one of a laser scanning display and au image projection device. The laser scanning display is typically implemented using micro-electromechanical system (MEMS) technology or any other light steering module, allowing for low energy consumption. However, it should be understood that any type of suitable technology may be used for generating the graphical information.
In a preferred embodiment the head-up display further comprises a control unit electrically connected to the actuator/motor of the lens arrangement for automatically adjusting the graphical information distance. The control unit may typically be arranged to receive information relating to the speed of the vehicle, the elevated height of the driver compartment, information relating to obstacles such as other vehicles, pedestrians, and road defect, and control the graphical information distance based on the received information. The control unit may for example be connected to an ECU/ECM (Electronic. Control Unit/Engine Control Module), where the ECU/ECM is comprised with the vehicle.
In an embodiment the graphical information to be projected includes at least one of an image and a video. The image/video may include information providing at least, one of guidance and a warning to a driver of, the vehicle. Other information as discussed above, e.g. current vehicle speed, the rotational speed of an engine comprised with the vehicle, the fuel level, and traffic/navigation data may be projected on the combiner and thus displayed to the driver of the vehicle. Providing a warning or relevant information to the driver has been identified as specifically advantageous. In addition, by using the disclosed HUD arrangement, it may also be possible to provide e.g. driver coaching information provided from vehicles or infrastructure within the vicinity (V2V, V2I), information relating to a platooning scenario (typically for trucks), etc.
In a preferred embodiment of the invention, the head-up display is comprised as a component of the vehicle. The vehicle could be any type of ground vehicle, for example a truck, a car, a bus, any type of construction vehicles/equipment, any type of war vehicles, a motorcycle, etc.
According to another aspect of the present invention there is provided a method for operating a head-up display arrangement for a vehicle having a windshield, the head-up display arrangement comprising a combiner, the combiner embedded on or arranged in a vicinity of or embedded on the windshield, a projector optically connected to said combiner, said projector projecting graphical information on said combiner, the graphical information perceived at a virtual distance in front of the combiner, and a lens arrangement arranged in an optical path between the projector and the combiner, the lens arrangement comprising a plurality of axially aligned lenses wherein the method comprises determining a vehicle related parameter, and adjusting an operational parameter for the head-up display arrangement based on the vehicle related parameter, wherein the vehicle related parameter comprises at least one of speed of the vehicle, a vehicle operational condition, and an operational condition for a driver of the vehicle, and the operational parameter for the head-up display arrangement comprises at least one of the graphical information distance and a view angle. This aspect of the invention provides similar advantages as discussed above in relation to the previous aspect of the invention.
According to a still further aspect of the present invention there is provided a computer program product comprising a computer program product comprising a computer readable medium having stored thereon computer program means for operating a head-up display arrangement for a vehicle, the head-up display arrangement comprising a combiner arranged in a vicinity of a windshield of the vehicle, a projector optically connected to said combiner, said projector projecting graphical information on said combiner, the graphical information perceived at a virtual distance in front of the combiner, and a lens arrangement arranged in an optical path between the projector and the combiner, the lens arrangement comprising a plurality of axially aligned lenses
wherein the computer program product comprises code for determining a vehicle related parameter; and code for adjusting an operational parameter for the head-up display arrangement based on the vehicle related parameter, wherein the vehicle related parameter comprises at least one of speed of the vehicle, a vehicle operational condition, and an operational condition for a driver of the vehicle, and the operational parameter for the head-up display arrangement comprises at least one of the graphical information distance and a view angle. Also this aspect of the invention provides similar advantages as discussed above in relation to the previous aspects of the invention.
The computer readable medium may be any type of memory device, including one of a removable nonvolatile random access memory, a hard disk drive, a floppy disk, a CD-ROM, a DVD-ROM, a USB memory, an SD memory card, or a similar computer readable medium known in the art.
Further advantages and advantageous features of the invention are disclosed in the following description and in the dependent claims.